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<script>
// 冒泡排序
// factorial
// 作用：将 1 ~ n 的阶乘
function factorial(n) {
  if (n === 1) {
    return 1;
  }
  return n * factorial(n - 1);
}

factorial(3)
// 1 ->  3 *     factorial(3 - 1)
// 2 ->  3 *     2 * factorial(2 -1)
// 3 ->  3 *     2 *  1




</script>